These studies involve five approaches to the attempted association between virus infection and glomerulonephritis. (1) Sera from patients with renal biopsy-proven kidney diseases of all types will be titered for viral antibodies and the distribution of antibodies correlated with the histologic parameters of renal disease utilizing a computer program. (2) Renal biopsies wll be examined by immunofluorescene for the presence of viral antigen. (3) Eluates of immunoglobulins will be obtained from nephrectomized diseased kidneys and tested for viral specificity by microtiter and immunofluorescence against virus infected tissue culture cells. (4) Cells from renal tissue obtained at nephrectomy or biopsy will be cultivated in long-term culture. By alterations in medium and physical and chemical manipulation, attempts will be made to rescue an identifiable virus from human kidney. (5) Animal models of acute viral glomerulonephritis will be examined to determine the variables resulting in progression to chronic renal failure.